Heat oil in a large pot over medium heat. Add onion and garlic; cook and stir until onion softens and turns translucent, about 5 minutes. Add chicken broth, sugar, mustard, and vinegar; bring to a boil over high heat. Stir in kale; cook, covered, until wilted, about 5 minutes.

Add dried cranberries; boil, uncovered, until liquid reduces by about half and cranberries soften, about 15 minutes. Season with salt and black pepper. Sprinkle with sliced almonds before serving.